1. Field of the Invention
The invention relates to a method for cooling the operating medium in a drive unit for conveyor system, in particular chain Conveyor Systems. Furthermore, the invention is applicable to a drive unit of a conveyor system, in particular a belt drive system.
2. Description of the Related Art
It is known in conveyor systems, in particular in chain conveyor systems, for achieving a slow, pressure-free acceleration of the system, damping of load surges and for load equalization, to use drive units with a hydrodynamic clutch. Thus, above all, a power transmission free from wear, a balanced starting-up of the motor and a gentle acceleration of the heaviest masses should be achieved. Particularly when used in mining, it is customary to operate these clutches with the operating medium water. To achieve the dissipation of heat during continuous operation, these clutches and the operating medium circuit are designed so that operating medium is discharged constantly from the working circuit of the clutch and thus the heat produced during the power transmission is dissipated. Two systems are generally used
1. an open system; and PA1 2. a closed system. PA1 1. solely at the time when the driving machine is set in operation and there is thus a related requirement of removal of the residual filling from the working chamber of the hydrodynamic clutch; andor PA1 2. in the case of a common connection of the inlet pipe for the purpose of volumetric cooling.
When using an open system, the clutches are supplied from a fresh water pipe. When using a double clutch, i.e., a clutch with two circuits, the water control arrangement contains two water circuits--also referred to as working circuits. At start-up, the latter are filled with a large volumetric flow, whereas in continuous operation there is a switch to a reduced volumetric flow in the system. The latter serves for dissipating the heat produced at the time of power transmission.
On account of the continuous throughflow of operating medium, i.e., the continuous uniform supply and discharge of fresh water into and out of the working chamber, the entire system is simple and has a very small construction. A separate cooler for the dissipation of the occurring slip heat from the operating liquid is not necessary. However, the high water consumption is a drawback, since fresh water must be prepared continuously for passage through the clutch. The preparation may be problematic depending on the application.
A second known possibility consists of conveying the operating medium in a closed system with an integrated cooling device. For this purpose, the clutches are supplied from a tank by way of connecting lines in the form of hoses. The tank is located below the level of the clutches. The operating fluid from the clutch, in particular the working chamber, can thus flow back into the tank due to gravity. However, for operation, a pump is required, which conveys the operating medium located in the tank into the working circuit of the clutch. On account of the power transmission by the operating medium, the latter heats up. Spray nozzles are therefore provided on the outer periphery of the clutch, by way of which a gradual escape of the operating medium takes place. The discharged, heated, operating medium collects in the operating medium collecting or clutch housing and from there returns to the tank due to gravity.
A closed system of this type is characterized in particular by a water-saving method of operation, however, an increased number of components and elements also has an increased space requirement, in particular on account of the necessity of providing feed lines between the tank and clutch and on account of the difference in height between the working chamber and the tank necessary in order to achieve the return flow.